Electro-thermal relay with heat augmentation



April 1966 w c. BROEKHUYSEN I 3,244,840

ELECTRO-THERMAL RELAY WITH HEAT AUGMENTATION Filed May 31, 1963 2 Sheets-Sheet 1 F I6. I F' l G. 2 4 R 15 H IO 6 501 L 2 20 18 IO SOURCE O Somzca I3 SOURCE SOURCE INVENTOR. WILLIAM C. BROEKHUYSEN ATTORNEY April 1966 w. c. BROEKHUYSEN I 3,244,840

ELECTRO-THERMAL RELAY WITH HEAT AUGMENTATION Filed May 51, 1963 2 Sheets-Sheet 2 F I G. 5 F' l G. 6

I I Z a Z 6 SOURCE SOURCE FIG. 7

P QC 2 D F 2 O 0 U l.- a (I I I I I I I TIME 2 INVENTOR. WILLIAM C. BROEKHUYSEN ATTOR NEY United States Patent 3,244,840 ELECTRO-THERMAL RELAY WITH HEAT AUGMENTATION William C. Broekhuysen, New York, N.Y., assignor to G-V Controls Inc., Livingston, N.J., a corporation of New Jersey Filed May 31, 1963, Ser. No. 284,533 5 Claims. (Cl. 200122) This invention relates to an Electro-Thermal System. It relates more particularly to such a system including a pair of electrical contacts, a member mechanically coupled to those contacts and energizable thermally to operate them, and an electric heater thermally coupled to that member to supply heat theretothe group of elements just described being frequently referred to as a thermal relay.

In such relays the output or work contacts, frequently the only ones present in the relay, tend to be operated with considerably less rapidity and force than commonly characterize the operation of magnetic relays. A broad object of the invention is to increase the rapidity and/ or the force-i.e., to increase the energy-with which the output contacts operate.

Such relays are frequently used in systems for the sensing of a variable electric quantity (such as a voltage or a current) or, more specifically, for the invoking of some action when for any appreciable time interval that quantity has equalled or passed a predetermined value. It is a particular object of the invention to provide an improved system for such sensing.

Such relays are one the other hand often used in systems for providing a time delay between their energization and the occurrence of some action which they are to invoke. It is another particular object of the invention to provide an improved system for such time-delay function.

According to one aspect of the invention the contacts are of the so-called normally open variety and are closed upon sufiicient thermal energization of the member initially mentioned above, and in the system there is incorporated a means associated with the member and rendered eifective by the contacts upon their closure for supplying additional heat to the member.

According to another aspect of the invention the contacts may be either normally open or normally closed and are operatedi.e. placed in the reverse of their normal conditionupon the sufficiently continued passage of electric current through a circuit in which there is connected the heater initially mentioned above, and in the system there is incorporated a means external to that cir cuit and rendered effective by the contacts upon their operation for supplying additional heat to the member.

According to another aspect of the invention the contacts are again either normally open or normally closed; there is provided a work elemet which has a mechanical coupling with the member at least after the contacts have been operated and which is operable by the member upon the supply of additional heat thereto, and in the system there is provided a means associated with the member and rendered effective by the contacts upon their operation for supplying additional heat to the member to operate the work element. The work element may when desired be a second pair of contacts, typically the output or work contacts of the system.

In accordance with an aspect of the invention peculiar to sensing, the electric quantity to be sensed may be applied to the heater, the member thereby heated may operate the contacts when for any appreciable time interval that quantity equals or passes a predetermined value, the contacts upon their operation may cause the supply of 3,244,848 Patented Apr. 5, 1966 additional heat to the member, and output contacts may be operated by the member upon that supply of additional heat.

In accordance with an aspect of the invention peculiar to time delay, a pair of work or output contacts may be arranged to be delayedly operated by the member when the latter is thermally energized at a predetermined power level, the member is initially energized at a lower power level, and upon an accumulation of energy supplied at that lower power level the energization of the member is increased to the predetermined power level.

Various objects of the invention have been stated above and others made apparent in the foregoing brief description. Allied and still other objects will appear from. the following detailed description and the appended claims.

In the detailed description reference is had to the accompanying drawings, in which:

FIGURES 1, 2, 3, 4, 5 and 6 are respective schematic circuit diagrams illustrating as many respective embodiments of the invention; and

FIGURE 7 is a set of curves referred to in connectionwith the description of typical operation of the invention for certain time-delay purposes.

Reference being had to FIGURE 1, there will be seen a schematic showing of a thermal relay R which in general structure may be similar to that shown on sheet 2 of the drawings of US. Patent No. 2,948,788 issued on my application and described in that patent with relation to that sheet. In the present schematic showing the metallic frame 11 of the relay is fractionally illustrated as of inverted J shape. Connected in effectively pivotal manner to the inside surface of the J near its fold is an essentially rigid arm 13 whose lower or free end portion may be folded for a short distance away from the frame 11 and then again folded so that the very extreme portion is essentially parallel to the main portion of the arm. Between the free end of the arm and a point adjacent the end of the foldof the I there is secured a metallic member in the form of a ribbon 15. The arm 13 is biased to counterclockwise rotation (as viewed in FIGURE 1) about its pivotal connection to the frame, as by the tension'of a spring 18 connected between it and the main portion of the frame; the etfect of this biasing is to place the ribbon member 15 under tension and to cause it and the arm 13 to assume such respective positions as are typically illustrated-which, if ribbon member and arm be of similar coefficients of thermal expansion, will be independent of ambient temperature. The main portion of the arm 13 may be extended a short distance further downwardly by a projection 14, through which there may extend an adjusting screw 17 which may form a means mechancially coupling the ribbon member 15 to the contacts hereinafter described. The securing of the ribbon member 15 above described may desirably be by spotresults in the generation of heat and its supply to the ribbon member 15; the elongation of that member resulting from its increased temperature-not duplicated in the temperature of the arm 13permits that member,

and with it the arm 15 and projection 14 and screw 17, to swing counterclockwise (as viewed in FIGURE 1) under the influence of the spring 18 by a distance several times as great as the increment of length of the member at the conclusion of that interval.

15. Thus the thermally elongatable member 15 forms the underlying means by which the contacts hereinafter described are operated.

Reference may be had to the patent mentioned above for preferred details of construction, and for a fuller explanation of the theory of operation, of such a thermal relay as has been thus briefly described.

Secured in the relay R in cantilever, and for example generally parallel with the arm 13, are a pair of contact springs 22 and 23 respectively carrying contacts 24 and 25. The spring 22 may be the nearer to the arm 13 and may be lightly biased against the end of the screw 17, while the spring 23 may be the further from the arm 13 and may hold its contact 25 in a position wherein it will not be engaged by contact 24 in the absence of substantial energization of the heater 2!). Sufficient such energization, however, will move the spring 22 against its light bias to carry its contact 24 into engagement with the contact 25. A small piece 21 of mica secured on the spring 22 opposite the screw 17 may serve electrically to isolate that spring from-the frame 11 and arm 13 when such isolation is desirable. By means of the adjusting screw 17 the inter-contact relationship will be adjusted so that the sufiicient energization just referred to is established appropriately to the intended function of the relay.

That function may for example be the sensing of a variable electric quantity-cg. a varying electric voltage or current-and more specifically the invoking of some action when for any appreciable time interval (whose magnitude is established by the relays thermal inertia) the voltage across or current through the heater has equalled or passed a predetermined value; for such a function the screw 17 may for example be adjusted so that when the predetermined value of voltage or current has been maintained across or through the heater for a time long enough for essentially complete stabilization of the screw position (i.e., for thermal saturation of the relay) the screw will just have carried contact 24 into engagement with contact 25. On the other hand that function may be the invoking of some action at the conclusion of a predetermined time or delay interval following the inception of energization of the heater from an essentially constant-voltage source, in which case the screw 17 may be adjusted so that the progressive movement of spring 22 which begins at that inception will just have carried contact 24 into engagement with contact 25 FIGURE 1, showing a pair of conductors 2 and 3 (one of them having therein the switch 4) respectively connected to the two terminals of an electric source 1, with a circuit 5 connected between the conductors and with the heater 20 interposed in that circuit for energization from those conductors, shows a system inherently adapted for either of those functions.

It is a feature of the invention that the closure of the contacts 24-25 results in the supply of additional heat to the member 15. For this purpose the contacts are shown in FIGURE 1 as serially interposed in a circuit which is connected between the conductors 2 and 3 and in which there is serially included a supplementary heater 50 which, like the main heater 20, is thermally coupled to the ribbon member 15. It will be understood that if the regulation of the voltage across the conductors 2 and 3 be perfect, then, no matter how small the additional heat developed in the supplementary heater 50 (so long as it is finite) may be, the closure of the contacts 24-25 with even infinitesimalpressure will occasion some additional supply of heat energy to and consequently some elongation of the ribbon member and thus some increase of the pressure of contact 24 against contact 25 i.e., some increase of the mechanical energy of operation of those contacts. (Obviously the same effect is achieved, with an underregulated voltage across the conductors 2 and 3, if the additional heat be sufficient at least in some degree to overbalance the reduction of heat in the main heater 2t} incident to the drop of inter-conductor voltage upon the completion of the circuit 10 by contact closure. Accordingly the energy of contact operation-in this embodiment, of contact closure-is regenerative, in that operation of those contacts with even infinitesimal mechanical energy results in an increase of the heat energy in the member 15 and thus an increase of the mechanical energy of operation of those same contacts. There are a wide variety of thermal-relay applications in which this feature contributes importantly to positiveness and reliability of action, this being particularly true in the case of sensing uses.

Especially since the supplementary heater 50 need often consume very litle power indeed, the circuit 10 in which it is connected may frequently be used as the circuit in which there is connected a load which is to be energized by the relay-for example a single load L to be energized at the conclusion of a timing interval or when the voltage across or current through the heater has for any appreciable time equalled or exceeded the predetermined value. Thus for many purposes the circuit of FIGURE 1 may be employed with only the elements thus far described.

I have, however, observed that the supply of additional heat to the member 15 upon the operation (in FIGURE 1 the closure) of contacts 24-25 may advantageously be utilized to perform functions other than those above indicated. Thus the additional heat may, by suitable establishment of the power in the supplementary heater 50, be made enough so that the resulting further elongation of member 15 and movement of elements 13, 14 and 17 will be suflicient to operate a work element which has a mechanical coupling to the member 15 at least after the contacts 24-25 have been operated.

While such a work element may be any device requiring for its operation a modest mechanical movement, I have illustrated it in FIGURE 1 as comprising a pair of contacts 28 and 29 respectively carried by contact springs 26 and 27 which may be successively disposed beyond spring 23 and of which spring 26 may be-mechanically interlinked with spring 22 as dottedly illustrated in FIG- URE 1. When the work element comprises such a structure its operation may be the operation (e.g., the closure) of those contacts, which may for example be normally (i.e., in the absence of all energization) be somewhat more widely spaced from each other than are the contacts 24-25 at that time. This operation of contacts 28-29 may in turn perform some electrical function, such for example as the energization of another load Mby way of ex ample only, from the conductors 2 and 3, for which purpose the spring 26 may be connected to the conductor 2, the spring 27 may be connected to one terminal of the load M, and the other terminal of that load may be connected to the conductor 3.

It will of course be understood that the load M may be the only load employed in the system, the load L then being omittedtypical.ly in the circuit of FIGURE 1 replaced by a simple resistor if necessary to the establishment of a proper power in the supplementary heater 50.

At least when a load to be controlled by the relay draws a substantial current or is an inductive load, it is particularly favorable to place it in the circuit position of M and to employ the contacts 28-29, rather than the contacts 24-25, for its immediate control; this leaves the contacts 2425--which in spite of possible long-continued use should remain in an unimpaired condition in order that the accuracy of timing or sensing by the relay be most fully maintainedfree of the contact eroding and other unfavorable influences of high or inductively peaked currents passing therethrough.

In the circuit of FIGURE 1 the means rendered effective by the closure of the contacts 24-25 for suppling additional heat to the thermally elongatable member 15 is external to the circuit 5 in which the main heater 20 is connected. At least in cases wherein no load at the circuit position of L is to be provided, it may be more convenient to provide such means in (rather than external to) that circuit 5, thereby permitting the elimination of the circuit 10. This may be done, and the function of supplying additional heat to the elongatable member upon closure of the contacts 24-25 still performed, by connecting in series with the main heater (now the only heater, and designated as 70 by reason of typical structural differences hereinafter described by way of example) a resistor 51 and by connecting those contacts across that resistor, as shown in FIGURE 2. The contact closure, shorting out the series resistor 51, will raise the voltage across and thus the power in the heater 7t) and will thus supply additional heat to the elongatable member.

It is to be understood that while in FIGURE 1 (and in various later figures) I have shown a thermally elongatable member comprising a ribbon (as in the relay shown on sheet 2 of the patent above referred to), no unexpressed limitation thereto is intended. There may instead be employed, for example, either of the constructions respectively shown in detail on sheets 1 and 3 of the patent, comprising respectively an internally heated (and optionally slugged) rigid metallic timing shell, and a grid of wires directly heated by the passage of an electric current-therethrough-the former being appropriate to longer time intervals or more sluggish sensing, and the latter to shorter time intervals or more delicate sensing,

than is the externally heated ribbon member of FIGURE Purely by way of example there has been illustrated FIGURE 2 the internally heated timing shell 65 in the form of a rigid metallic case having at its ends metal- :lic tabs 64 which are respectively secured (e.g., spotwelded) to the ends of frame 11 and of arm 13 and having an electrical heater 70 contained therewithin (and electrically suitably insulated therefrom). If desired there may also be included within the shell one or more slugs or blocks 69 of metal whose function is further to increase the thermal capacity of the member, which is in any event much greater than that of a thin ribbon. By "reason of the difference of its elongatable member, the relay of FIGURE 2 is designated as R; from it any spring such as 18 may be omitted, since the shell 65 itself exerts force in longitudinal expansion as well as contraction.

1 Further by way of example of permissible variation FIGURE 2 shows the contacts 28-29 and the load M serially connected across a second electric source 6, rather than. across the source 1 which supplies heating energy to the relay.

' The advantages of the structure of either FIGURE 1 or FIGURE 2 (and of other figures still to be described) 'is by no means confined to sensing applications, but extends to time-delay applications as well. A particular and important utility of the structure, when the contacts 28-29 are included, is its use to provide a longer delay interval,

for a greater speed of contact movement at the instant of .ment of the contact arms 22 and 26 and thus of the con- ,'.tact 28, plotted against time of thermal energization of the elongatable member (15 or 65) at a predetermined "power level; the horizontal dash-dot line Z may represent 'the displacement at which the contact 28 will be closed .against the contact 29. The abscissa T of curve A at fthat curves intersection with the line Z represents the interval of delay with which if contacts 24-25 were ab- .sent or electrically disconnected the relay would operate;

ithe slope of the curve A at the intersection would be a measure of the speed of contact movement at the instan of contact operation.

If it now were desired that the relay operate with twice the delayi.e., at time T -there are two known alternatives to either of which resort may be had. One of these would be to reduce somewhat from the original predetermined level the power at which the elongatable member is energized (i.e., the power supplied to the heater), and curve B typifies the contact movement which would result; its slope at the intersection with line Z is, however, less than one fourth of that of line A, entailing unsatisfactory operation of the contacts 28-29which are the output or work contacts of the relay. The other alternative would be to leave the power of energization at the original predetermined level but to increase the mass, or thermal capacity and thus inertia, of the elongatable member, and curve C typifies the contact movement which would then result; its slope at the intersection with line Z, though greater than that of curve B, is nevertheless still only half that of curve A.

In accordance with this aspect of the invention I achieve the longer (e.g. doubled) delay and at the same time rapid contact movement at the instant of operation. To do this I may leave unaltered the mass or thermal capacity of the relay whose operation is typified by curve A; I initially energize the elongatable member at a substantially lower power level; and I utilize the contacts 24-25 :as a means, operated by the elongatable member upon an accumulation by it of energy supplied at that lower power level, to increase the energization of the elongatable member to energization at the predetermined power level.

The resulting movement of contact 28 is illustrated by the curve D, in which the point D represents the point of shift of energization of the elongatable member from the substantially lower to the predetermined power level. The slope of the curve D at its intersection with the line Z-i.e. the speed of contact-28 movement at the instant of operationis essentially the same as that of curve A, in spite of the delay having been typically doubled. (It is true that the speed of contact-24 movement at the instant of its closure against contact 25 is not great, but this is of small consequence in view of the facts that contacts 24-25 are not output or work contacts and that the additional heating power which they control may be both modest and supplied to a wholly non-inductive heater.)

It will readily be understood that if the desire were to achieve faster contact movement at the instant of operation instead of the longer delay, the same technique would be used excepting that the mass or thermal capacity of the elongatable member would be appropriately reduced.

Further figures illustrate the amenability of the invention to change in respect of various circuit arrangements. Thus instead of shorting out the resistor 51 of FIGURE 2 the closure of the contacts 24-25 may be made to short out a portion of the main heater itself, thereby decreasing the resistance of the active heater and in that manner increasing the power therein. This is shown in FIGURE 3, which again by way of example shows the elongatable member in the form of -a ribbon 15 with external heater (now designated as 20 in view of its greater extension along the member 15); therein the heater 20' is provided with a tap 52 and the contacts 24-25 are connected across the portion of the heater which intervenes between that tap and the conductor 2.

There are important thermal-relay applications in which the operation to be performed by the relay at the end of its timing or delay interval or when it senses the predetermined voltage or current is the open-circuiting, rather than the energizing, of a load. FIGURE 4 shows a load N to be open-circuitcd. In it the contacts 23-29 which were in series with the load M of earlier figures have been replaced by a pair of contacts 58 and 59the latter being for example a second contact carried by spring 23, and the former being carried by a contact support 56 which need not be resilient-which are normally closed 7 and are to be opened upon the supply of additional heat to the elongatable member 15.

It will be obvious that in the operation of each of the embodiments of FIGURES 2, 3 and 4 there is the same regenerative action as in the case of FIGURE 1i.e. the closure of the contacts 24-25 with even infinitesimal energy results in an incraese of the energy of closure of those same contacts, in view of the additional heat supplied to the member 15 upon the very initial closure.

I prefer, other considerations being equal, one of the arrangements of FIGURES l, 2, 3 and 4 by reason of the normally open condition of their first-to-operate contacts 2445, which insures that any tendency toward sticking of those contacts will be confined to the ordinarily uncritical portion of the operative cycle when the system is deenergized and the substantial force relatively rapidly developed on cooling of the elongatable member is available to de-stick or open them; any influenw of the unfavorable tendency on the frequently critical timing or sensing by the system is then wholly obviated. It is, however, true that with suitable choices of contact material or with some conditions of operation of the system, or both, such tendencies may be wholly negligible or of negligible adverse consequence, and in certain of its aspects the invention contemplates the arrangement of the first-to-operate contacts, then for distinction designated as 24' and 25' respectively, as normally closed contacts.

That arrangement being employed wherein (as in FIG- URE 1) the means for supplying additional heat to the member 15 is external to the main-heater circuit 5, the normally closed contacts 2445' may be arranged for example as shown in FIGURE 5. Therein the spring carrying contact 24' is made shorter and designated as 22, and the spring carrying contact 25' is made longer and designated as 23', in order that the screw 17 may act on spring 23'; that screw will of course normally (i.e., with the relay at ambient temperature) be appreciably spaced from that spring. The spring 26 will be mechanically interlinked with the spring 23. FIGURE 5 further differs from FIGURE II in that the supplementary-heater-including circuit 10 of that figure is replaced by a circuit 9 in which no contacts are serially interposed but which does include a current-limiting resistor 49 preferably adjacent conductor 3; this circuit 9, if it includes any load "L, will preferably include that load adjacent the conductor 2. The normally closed contacts 24'25 will be connected across the serial combination of the supplementary heater 50 and the load L if employed, or across the supplementary heater alone if there be no load L. When the system is first energized the supplementary heater 5t), and the load L if employed, will stand shorted out by the contacts 2d- 25', while the contacts 23-29 will of course stand in their normally open condition. The screw 17 will have been so adjusted that the contacts 24'25 will be opened at the time or under the condition when the contacts 24Z5 of earlier figures would have been closed; the energy of operation-in this case of the opening-f contacts 24145 will of course be regenerative, in analogy to the regenerative energy of closure of the contacts 2425 of earlier figures, in view of the additional heat supplied to the member 15 upon the very initial opening. Obviously the contacts 28-29 of FIGURE might be replaced by some other work element, as above disclosed in connection with earlier figures.

The normally closed contacts 24'25 may alternatively be employed in an arrangement in which the means for supplying additional heat to the member 15 is not external to, but instead comprises means for altering the current in, the main-heater circuit 5, in general analogy to the circuit of FIGURE 3. This is typically illustrated in FIGURE 6, in which the main-heater circuit 5 is provided (preferably adjacent the conductor 3) with a voltage-dropping resistor 61 and in which the normally closed contacts 24-25 ordinarily place a resistor 62 in shunt to the main heater (now itself designated as 20" in view of further altered normal voltage). The additional heat is again supplied to the member 15 upon the opening of 2 'l25'in this case by the increase of current through and voltage across the heater 20" attendant on the thenoccurring open-circuiting of the shunt resistor 62, again with the effect of rendering regenerative the energy of opening of the contacts 24/415. FIGURE 6 by way of example only shows the output contacts, designated as 28' and 29, as contacts normally closed under greater pressure than are 2425, respectively carried by springs 26' and 27 (of which the latter is now mechanically coupled to 23'), and opened when 28-29 of FIGURE 5 would be closed.

It will be understood that while I have disclosed my invention in terms of particular embodiments thereof, I do not intend thereby any unnecessary limitations. Thus while I prefer and have disclosed the thermally energizable member which operates the contacts as being a thermally elongat-able one, obviously other types of members (such for example as a bimetallic arm which deflects when energized) may alternatively be employed. That and many other modifications will be suggested by my disclosure to those skilled in the art, and such modifications will not necessarily constitute departures from the spirit of the invention or from its scope, which I undertake to define in the following claims.

I claim:

1. In an electrical system operable from a source of electric energy, the combination of a pair of contacts, a member mechanically coupled to said pair of contacts and thermally energizable to effect the closure thereof, an electric heater thermally coupled to said member to sup-v ply heat thereto, a circuit connectible to the source and in which said heater is connected for energization, and means for rendering regenerative the energy of closure of said contacts, comprising means associated with said member and rendered effective by said pair of contacts upon closure thereof for supplying additional heat to said member.

2. In an electrical system operable from a source of electric energy, the combination of a pair of cont-acts, a member mechanically coupled to said pair of contacts and thermally energizable to effect the operation thereof, an electric heater thermally coupled to said member to supply heat thereto, a circuit connectible .to the source and in which said heater is connected for energization, and means for rendering regenerative the energy of operation of said contacts, comprising means external to said circuit and rendered effective by said pair of contacts upon operation thereof for supplying additional heat to said member.

3. In an electrical system operable from a source of electric energy, the combination of a pair of contacts, a member mechanically coupled to said pair of contacts and thermally energizable to effect the operation thereof, an electric heater thermally coupled to said member to sup ply heat thereto, a circuit connectible to the source and in which said heater is connected for energization, a work element mechanically coupled with said member at least after said contacts have been operated and operable by said member upon the supply of additional heat to said member, and means for rendering regenerative the energy of operation of said contacts and causing the operation of said work element, comprising means associated with said member and rendered effective by said pair of contacts upon operation thereof for supplying additional heat to said member.

4. In an electrical system operable from a source of electric energy, the combination of a pair ofcontacts, a member mechanically coupled to said pair of contacts and thermally energizable to effect the operation thereof, an electric heater thermally coupled to said member to supply heat thereto, a circuit connectible to the source and in which said heater is connected for encrgization, a second pair of contacts mechanically coupled with said member at least after said first-recited pair of contacts has been operated and operable by said member upon the supply of additional heat to said member, and means for rendering regenerative the energy of operation of said firstrecited pair of contacts and causing the operation of said second pair of contacts, comprising means associated with said member and rendered effective by said first-recited pair of contacts upon operation thereof for supplying additional heat to said member.

5. In an electrical relay system for sensing a variable electric quantity, the combination of a thermally energizable member, an electric heater to which said electric quantity may be applied and which is thermally coupled to said member, a pair of sensing contacts, to which said member is mechanically coupled, operated by said memher when for any appreciable time interval said quantity equals or passes a predetermined value, means for render- 1% ing regenerative the energy of operation of said contacts comprising means rendered effective by said sensing contacts upon operation thereof for supplying additional heat to said member, and a pair of output contacts operated by said member upon such supply of additional heat.

References Cited by the Examiner UNITED STATES PATENTS 1,402,417 1/ 1922 Hamilton 200-113 2,498,127 2/1950 Kuhn 2l19--511 X 2,732,476 1/1956 Smith 219511 X 2,939,933 6/1960 Manganaro et al. 2()0122 BERNARD A. GILHEANY, Primary Examiner.

L. A. WRIGHT, Assistant Examiner. 

1. IN AN ELECTRICAL SYSTEM OPERABLE FROM A SOURCE OF ELECTRIC ENERGY, THE COMBINATION OF A PAIR OF CONTACTS, A MEMBER MECHANICALLY COUPLED TO SAID PAIR OF CONTACTS AND THERMALLY ENERGIZABLE TO EFFECT THE CLOSURE THEREOF, AN ELECTRIC HEATER THERMALLY COUPLED TO SAID MEMBER TO SUPPLY HEAT THERETO, A CIRCUIT CONNECTIBLE TO THE SOURCE AND IN WHICH SAID HEATER IS CONNECTED FOR ENERGIZATION, AND MEANS FOR RENDERING REGENERATIVE THE ENERGY OF CLOSURE OF SAID CONTACTS, COMPRISING MEANS ASSOCIATED WITH SAID MEMBER AND RENDERED EFFECTIVE BY SAID PAIR OF CONTACTS UPON CLOSURE THEREOF FOR SUPPLYING ADDITIONAL HEAT TO SAID MEMBER. 